Sinosophiopsis (Brassicaceae), a New Genus Endemic to China

Abstract. The new genus Sinosophiopsis (Brassicaceae) is described, and its relationship to Sophiopsis is discussed. The new species Sinosophiopsis bartholomewii is described, and the new combination S. heishuiensis is proposed.

During the revision of Chinese Brassicaceae for the forthcoming volume 8 of the Flora of China, two species were initially set aside for future study. As the result of critical comparisons of these two taxa with most of those of the known Eurasian genera, the conclusion reached is it to place them in a new genus, hereafter known as Sinosophiopsis.

Sinosophiopsis, which is endemic to China, is most closely related to the central Asian genus Sophiopsis. Both genera consist of annuals with incumbent cotyledons, reticulate and mucilaginous seeds, pinnatisect leaves, terete fruits, and branched trichomes. Sinosophiopsis is easily distinguished by having white flowers, linear and strongly torulose fruits, angled and longitudinally striate stems, indumentum consisting of simple and forked trichomes, and ovaries (20 to)24- to 40-ovulate. By contrast, Sophiopsis has yellow flowers, elliptic, obovate, or narrowly oblong, usually non-torulose fruits, terete stems, indumentum of primarily dendritic trichomes only rarely mixed with simple ones, and ovaries 4- to 12(to 16)-ovulate.

One of the two species assigned herein to Sinosophiopsis was previously described by Wang (1987) as Cardamine heishuiensis, and that placement was followed by Tan et al. (1999) without further evaluation. Upon a casual examination of the species, it was immediately concluded that it should be excluded from Cardamine for two reasons. First, none of the approximately 200 species of this genus has branched trichomes, and second, all species of Cardamine have flattened repla, explosively dehiscent fruits, and valves spirally coiled during dehiscence (Al-Shehbaz, 1988). Sinosophiopsis heishuiensis has a mixture of simple and forked trichomes, terete repla, non-explosively dehiscent fruits, and valves remaining flat during fruit dehiscence. Full descriptions of both species of Sinosophiopsis are provided to facilitate a direct comparison.

Because of the limited number of collections available for both species of Sinosophiopsis, little can be said about their overall variability. The two species are readily distinguished from each other by the characters listed in the key below.

Sinosophiopsis bartholomewii is named in honor of Bruce Bartholomew (California Academy of Sciences), who organized two expeditions to Qinghai that led to the collection of this novelty, in recognition of more than two decades of devotion to Chinese botany.

Acknowledgments. I am profoundly grateful to Bruce Bartholomew for sending his collections of the Brassicaceae from Qinghai (China) for my study. I am indebted to Henk van der Werff for correcting the Latin and to Guanghua Zhu and Song Hong for their help in translating herbarium labels from the Chinese.